CoolingDiscuss all of the aspects of cooling that you can think of! Radiators, transmissions, electric fans, etc.

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My engine fan only turns on when I turn on the AC. Thus, it will just keep getting hotter and hotter when I'm in stop and go traffic, even in the winter. The only way to help is by turning on the AC.

I went to autozone and the guy there said I needed a "Coolant temperature sensor" (Wells part # SU109). It screws in right next to where the radiator hose mounts to the engine block and is made of copper. It has a plug on top with wires leading to the computer I guess.

Anyhow, I just put that in, and it didn't fix the problem. What could it be?

Coolant temperature sensor isn't the correct term for it. It is actually called a radiator fan switch. The coolant temperature sensor is on the intake manifold near the thermostat housing. The radiator fan switch is down on the passenger side head between #6 and #8 spark plug. Or it could be the relay.

I've got a similar problem, only my A/C doesn't like to turn on so sometimes I can't stop it from overheating by that method. What works for me (for whatever reason) is to turn the car off and restart it. Then the fans kick in. Go figure... any ideas on what might cause that?

I kept having stupid problems like this so I switched to a mechanical fan. Which didn't work to well. So I went ahead and reinstalled my electric fan. Wired it to run with the key and haven't had a problem since.

I've figured out my similar problems,but curious and open to ideas, I would liike to wire mine in full time aswell since I don't have plans to run the car much when it's cold and snowy out. What was your method of hardwiring it to the ignition?

Originally posted by chomp My engine fan only turns on when I turn on the AC. Thus, it will just keep getting hotter and hotter when I'm in stop and go traffic, even in the winter. The only way to help is by turning on the AC.

I went to autozone and the guy there said I needed a "Coolant temperature sensor" (Wells part # SU109). It screws in right next to where the radiator hose mounts to the engine block and is made of copper. It has a plug on top with wires leading to the computer I guess.

Anyhow, I just put that in, and it didn't fix the problem. What could it be?

I have a 92 Camaro RS 305 TBI

If the fan turns on with the AC that rules out the relay. As was posted, replace the fan switch on the block or I'll bet the wire is off. Wiring the fan for continuous operation is stupid. It will chew up the fan motor in short order and place undue stress on the charging system. The fan circuits may look complicated but they are actually very simple.

__________________ A man's intelligence is judged not by what he knows, but rather by his willingness to seek out differing points of view. A favorite saying of the Jesuits.

Saying it's "stupid" to hardwire the fan is kind of harsh don't you think? If you need to drive your car and don't have the time or resources to permanently fix the problem at the current time, I'd rather burn up my fan versus the motor wouldn't you?

Well, my motor stays at 185-195 (180* stat) all the time too. I have my '730 ECM programmed to turn the primary fan on at 195*, off at 187* along with my secondary fan switch that will come on at 200* or with the a/c... My fans shut off when they're not needed, just like its supposed to be.

All I'm saying is that if you think about it, there is a way to make the factory system do what you want, without wearing out your fans/alternator.

I know that running it full time is not the correct way, but, since I'm only driiving it a few more weeks before snow hits I have other things to consume my time, so what I was tryiing to say was that to get by that's what I'm going to do for now. I have troubleshooted the system, I have replaced the problem parts I have found. I do have a plan to uprgade the fan system to a more reliable dual setup over the winter while it's NOT IN USE. Right now I use the car while I get my winter driver ready (more of a priority). But, one thing I DO NOT plan to do over the winter is free up a deep fried motor, not a bad a rational for a stupid person I thnk.

I know we all have rigged something or another to make stuff work until we can focus on it and fix it correctly later, less face it, that's the nature of the beast.

I too am having a problem with the fan. Like someone stated before, the fan only comes on when the A/C is turned on.
I have replaced the radiator fan switch but the problem still exists. If I ground the wire to the radiator fan switch the fan comes on. I tried two different radiator fan switches from two different sources but it still dosn't come on.
Any ideas??

So..Chomp, instead of trying to argue about who knows better, I will tell you what I have learned from my experience. I had a very similar problem to yours. My 'maro always ran at a low temp, but one day it skyrocketed and overheated after coming home from a bball game where i was sitting a traffic lights for long periods of time. I looked into things, i checked all fuses...they were ok, and so were all relays. So then I took out the fan and ran a direct source of electricity to it and it ran, so i knew that the motor was fine. The next option is the temperature switch located on the right (passenger) cylinder head next to the solenoid. This should do the trick, I just need to get a new one and pop it in. Hopefully this gives you some insight into your own problem if you havent already fixed it.
~~91 RS

Originally posted by wrightz28 I've figured out my similar problems,but curious and open to ideas, I would liike to wire mine in full time aswell since I don't have plans to run the car much when it's cold and snowy out. What was your method of hardwiring it to the ignition?

Thanks in advance

I have a question along the same lines... My radiator is leaking EVERYTHING right now... I need to replace that but is this a reason the fan won't come on, or do I have even more issues to troubleshoot?
Great question/post! I had also heard a manual switch for the fan/s is certainly possible but have no source...was a magazine on GM cars me thinks
Bill

Well, like I said earlier, I'm just going to start from scratch with the whole system and modify a little.

I'm going from the '85 1 fan setup to a later 2 fan. The primary will work on the standard automatic switch contrilled circuit and the secondary fan will be a manual toggle for need be situations. Given Chicago rush hour traffic I don't feel safe with just one fan and no back up to limp home (aside from jumping battery power direct, and again in Chi-town traffic and the neighborhoods I have to drive through, not a very safe option).

Ha!
No snow here, but I may have to drive mine anyway... Will be only operational one legal to drive first...hehe
The idea I'd imploy is a switch to turn on via the temp guage data. Controlling the cooling time and extent manually. If you always adhere to the guage and of course, know it's working!
Bill

Originally posted by Bill Speed Ha!
No snow here, but I may have to drive mine anyway... Will be only operational one legal to drive first...hehe
The idea I'd imploy is a switch to turn on via the temp guage data. Controlling the cooling time and extent manually. If you always adhere to the guage and of course, know it's working!
Bill

That's pretty much the idea, one to run normal, and one to turn on manually when the gauge creeps up. The gauge didn't work originally when I bought the car in August. Was one of those thigs that I wasn't worried 'bout. Figured I'd rather play with my new toy and straighten it out later since everything seemed normal, curse of the used car, you get someone else's botched-up jobs

Indulge me an OT bit: I recently got turned on to a Caddy engine swap site page via an eBay seller. HT4100.com I think it was, based on GM's HiTech 4.1 liter. This was swapped out to a stronger Olds V8 for the Eldorado/Seville cars of the 1980s.
This involves quite a bit of James Bond esq... Doing away with complicated wiring and computer control to diagnose most functions with new installed guages! It's amazingly complex...but in the end, done right, it works! Some orig circuits could remain in place as well...not w/o some bit of mods fun, but still cool
Bill

Originally posted by lsndrumline04 So..Chomp, instead of trying to argue about who knows better, I will tell you what I have learned from my experience. I had a very similar problem to yours. My 'maro always ran at a low temp, but one day it skyrocketed and overheated after coming home from a bball game where i was sitting a traffic lights for long periods of time. I looked into things, i checked all fuses...they were ok, and so were all relays. So then I took out the fan and ran a direct source of electricity to it and it ran, so i knew that the motor was fine. The next option is the temperature switch located on the right (passenger) cylinder head next to the solenoid. This should do the trick, I just need to get a new one and pop it in. Hopefully this gives you some insight into your own problem if you havent already fixed it.
~~91 RS

Hmmm. Okay I replaced the switch the goes next the the coolant intake into the block on the front center of the engine, and then I replaced another switch right under the exhaust manifold on the driver's side. What's this thing on the passenger side head you're talking about? What does it look like?

Originally posted by chomp Hmmm. Okay I replaced the switch the goes next the the coolant intake into the block on the front center of the engine, and then I replaced another switch right under the exhaust manifold on the driver's side. What's this thing on the passenger side head you're talking about? What does it look like?

I believe that's a temperature switch, which controls the 2ndary fan. Don't ask me what temperature it turns that fan on, though. You can find it between cylinders 6 and 8 (the two rear, passenger side cylinders). Btw, I think it's on the block, not the head.

The is a pretty good article on the technical boards about this problem. Read, digest and see what you think. Personally I just wired up to switches which when turned "ON" completed the ground on the fan relays. Granted this isn't working according to stock, however I can control the fans, thus control the temprature the car runs at. If anyone is curious your fan relay(s) will be right next to the battery, one on the radiator side next to the battery and one "behind" the battery on the front end. All the ECM / Tempratur switches do is complete the path to ground. Solder a wire onto that leg of the Relay plug and hook up some switches inside the car. Your fans will turn off when the ignition is off, PLus your not messing up the factory wiring at all. Just a idea.

Have ANY of you guys hooked a scan tool up to your engine and seen what the readings are from the CTS to the ECM? (and yes it does means Coolant Temperature Sensor).

The stock setting in the eprom is very high before it turns on FAN1. And FAN2 is only turned on by either installing a lower temperature Fans Switch OR repinning the wires to make the ECM control that too.

Your ECM is probably working EXACTLY as it was originally programmed by the factory and the easiest thing to do is reprogram the chip to properly control the fan to the T-stat you have. Also, when you turn on your A/C it WILL turn on Fan1 but only to 35 mph. It is not unusual to have the A/C put a higher load on the engine and Fan1 by itself is not sufficient to cool it.

That's when it's preferable to repin the connector to make Fan 2 become the primary fan and leave Fan1 for A/C and secondary fan. This way you will have BOTH fans working and your engine stays the coolest. And you don't need to remember to turn on any switches (or turn them off either). Let the computer do its job and you can concentrate on driving.

Originally posted by Glenn91L98GTA Have ANY of you guys hooked a scan tool up to your engine and seen what the readings are from the CTS to the ECM? (and yes it does means Coolant Temperature Sensor).

The stock setting in the eprom is very high before it turns on FAN1. And FAN2 is only turned on by either installing a lower temperature Fans Switch OR repinning the wires to make the ECM control that too.

Your ECM is probably working EXACTLY as it was originally programmed by the factory and the easiest thing to do is reprogram the chip to properly control the fan to the T-stat you have. Also, when you turn on your A/C it WILL turn on Fan1 but only to 35 mph. It is not unusual to have the A/C put a higher load on the engine and Fan1 by itself is not sufficient to cool it.

That's when it's preferable to repin the connector to make Fan 2 become the primary fan and leave Fan1 for A/C and secondary fan. This way you will have BOTH fans working and your engine stays the coolest. And you don't need to remember to turn on any switches (or turn them off either). Let the computer do its job and you can concentrate on driving.

I totally agree. I sucked it up a few days or weeks ago, spent a few hours figuring out exactly what every single wire in that system does. Now I know it like the back of my hand. It works fine for the time being. Sure, the fans come on at a really high temperature, but then it cools down to just under 220 and turns off. Under highway driving the fans never come on and the needle is pegged at 220. So, what I think my best solution is to get some chip burning equipment and change the fan-on temp to kick in much earlier than it does. What better of an excuse do you have to buy the tools that will help you tune your car for your mods and get maximum MPG and HP?

Throw some pics up regarding Repinning precedure, in case I'm likely not following... I used to hear the fan/s come on while inside the car, or letting it run, but not previously popping the hood to eyeball what had been working and when.

The electronics in any late model vehicle can be more then a handful and normally, I'd entrust someone already familiar, but if I can swing anything for little to no cash, I'll attempt it.

I still am having difficulty swapping out my old radiator as tools and weather are against me, but I'll be testing with water first to know if everything on that front is taken care of... By all accounts, after several minutes, 5 or more, the temp guage starts to really rise and the fan SHOULD kick in. I was being pretty careful operating with no coolent though, but it's a tad scary
BILL

Saying it's "stupid" to hardwire the fan is kind of harsh don't you think? If you need to drive your car and don't have the time or resources to permanently fix the problem at the current time, I'd rather burn up my fan versus the motor wouldn't you?

I apologize, poor choice of words. However I have seen so many posts about changing or redesigning how the cooling system operates to get around problems. Fact is that if the cooling system is operating correctly, system pressure, proper mix, good cap etc it will run within safe parameters. Running the fans all the time is not required and has some major pitfalls over the long haul.

__________________ A man's intelligence is judged not by what he knows, but rather by his willingness to seek out differing points of view. A favorite saying of the Jesuits.

I was sure I replaced my thermis. with a 190 degrees rating listed in the manuals I have. Most quote lower or modified with holes. I don't care to remove mine soon, so I hope I got the right one now.... for the L98, stock